# Question #60c57

##### 4 Answers

Q.7. Locomotive requires to exert constant force of

Force required to be exerted

Additional force is required to accelerate the train. We know that rate of change of speed is acceleration. Using Newton's Second Law of motion and inserting values in SI units we get

#F=ma#

#F=30000xx0.5=15000N#

Total force required

#17.04kN#

Q. 8. We know that

#"Power" ="work done"/"time taken"# ......(1)

Work done

#W="Force"xx"Distance"# .....(2)

Also

#"Force"=mg# ......(3)

where#m# is mass of object and#g# is acceleration due to gravity,#=9.8ms^-2#

Inserting values in equation (1) in SI units we get

#"Power" =(30000xx9.8xx24)/(0.5xx60xx60)#

#"Power" =7056000/1800=3920W#

#3.92kW#

Q. 9. Centrifugal force

#F_c=mromega^2# ......(1)

It is given that mass revolves about a point 2 meters from its centre of gravity.

Units of

Mass revolves at a speed of 60 revolutions per minute.

One revolution is equal to

Hence

Inserting values in (1) we get

#F_c=5xx2xx(2pi)^2#

#=>F_c=394.8N# , rounded to one decimal place.